Measuring and testing – Fluid pressure gauge – Diaphragm
Reexamination Certificate
2001-07-13
2004-05-11
Nolan, Jr., Charles H. (Department: 2854)
Measuring and testing
Fluid pressure gauge
Diaphragm
C073S716000, C073S724000, C073S725000, C073S861020, C073S861220, C073S861240
Reexamination Certificate
active
06732589
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pressure sensor, a method for manufacturing a pressure sensor, and an internal combustion engine having a pressure sensor.
BACKGROUND INFORMATION
Pressure sensors are used in various branches of engineering in order to measure the pressures of gases or liquids. The pressure sensors are often subjected to high loads that depend on the current state of the medium in which the measurement is performed. Frequently, the pressures acting on the pressure sensor vary considerably. A pressure sensor must therefore withstand high loads, and it must deliver exact measuring results.
Conventional pressure sensors include a diaphragm, which deforms in response to a pressure difference on the two sides of the diaphragm. The deformation of the diaphragm is measured by piezoelectric elements, which are situated on one side of the diaphragm.
In the case of high pressure or temperature loads, there is the problem of the pressure-sensor diaphragm twisting or warping in its frame or suspension. The consequences include inaccurate measurements or invalid measuring results, which occur in response to high pressure or temperature fluctuations.
Therefore, it is an object of the present invention to provide a pressure sensor, which delivers accurate measuring results, and may be configured so that it withstands high pressures, and functions reliably in the case of large pressure or temperature differences. It is another object of the present invention to provide a method for manufacturing such a pressure sensor which may be implemented quickly and cost-effectively. It is a further object of the present invention to provide a combustion engine that may attain lower emissions and/or an improved efficiency.
SUMMARY
The above and other beneficial objects of the present invention are achieved by providing a pressure sensor, a method for manufacturing a pressure sensor and a combustion engine as described herein.
The pressure sensor according to the present invention includes a housing, the interior chamber of which is sealed by a diaphragm, an arrangement configured to generate a signal in response to the diaphragm being deformed, and also a flexible measuring element, which is included in addition to, i.e., positioned separately from the diaphragm, and is coupled to the diaphragm. The arrangement configured to generate a signal being coupled to the flexible measuring element, in order to generate the measuring signal in response to the flexible measuring element deforming.
The pressure sensor according to the present invention prevents the measuring results from being invalidated by twisting or warping of the diaphragm. The additional, flexible measuring element positioned separately from the diaphragm allows measuring results to be achieved, which are still relatively accurate, even in the case of a diaphragm that is twisted or warped in itself. The pressure sensor may even perform accurate and reliable measurements in the case of high pressures or pressure differences, and/or in the case of sharply changing temperatures, the pressure sensor also having an increased service life.
The measuring element may include a bendable bar, one end of which is freely suspended. In this manner, a deformation of the diaphragm, which is caused by a pressure acting on the diaphragm, may be transmitted to the bendable bar, and the pressure may be picked up and measured separately from the deformation of the diaphragm. The measuring or deformation element may, for example, be formed in the shape of a tongue. The measuring signal is generated by the deformation of the measuring element. The bar may relax in response to undesired twisting or warping. This prevents the measuring results from being invalidated. In addition, the pressure sensor may include a stop element, which opposes the deformation force in response to a selected deformation of the measuring element. This arrangement provides overload protection against high pressures, the overload protection being independent of the output signal. That is, the measuring element may be designed for high sensitivity and nevertheless withstand relatively high pressures. Therefore, there is no loss of sensitivity at the measuring element, even in the case of high pressure loads. The pressure sensor may also measure the applied pressure under high pressure loads, without the danger of destroying the measuring element. The stop element may be rigid, so that the measuring element does not bend or deform further upon reaching the stop, or the stop element may be designed to be bendable or flexible.
The stop element may be in the form of a second, flexible measuring element, which, for example, is harder or flexurally stiffer than the first measuring element. This arrangement allows the pressure sensor to have a plurality of measuring ranges and to be, e.g., suitable for measuring in the low pressure range and also, or simultaneously, in the high pressure range. At relatively low pressures, only the first measuring element is initially deformed. The stop element or second, flexible measuring element also deforms at or beyond a selected deformation of the first measuring element.
Because of the high resistance of the stop element or second measuring element, the first measuring element only bends or deforms a little more, even at high, applied pressures, so that it is protected from overload. Thus, at or above a selected pressure, it is only possible to further deform the first and the stiffer, second measuring elements at relatively high pressures. Therefore, the second measuring element opens up an additional measuring range for relatively high pressures.
The stop element may be configured as a half-open or semienclosed diaphragm, or it may be tongue-like or a bendable bar, the end of which may be freely suspended. The stop element may be fixed on one end. The stop bar may be configured similarly to or exactly like the first measuring element.
The first measuring element and/or the second measuring element may be provided with one or more piezoelectric elements as the arrangement configured to generate signals. For example, the signal generation arrangement may include piezoresistors, which may be connected to a Wheatstone bridge.
The pressure sensor may include a deformable transmission element configured to transmit force between the diaphragm and the measuring element and/or the stop element. The transmission element may have a selected elasticity or bending resistance. For example, the measuring range or the measuring ranges of the pressure sensor are determined by the stiffness or hardness of the transmission element. In this manner, measurements may be performed at relatively high pressures applied to the diaphragm using a relatively soft measuring element having a high sensitivity.
The transmission element may be configured as a diaphragm and/or as a chip, and its thickness is selected for determining the measuring range or the measuring ranges of the pressure sensor. That is, the measuring range or the measuring ranges of the pressure sensor may be controlled by varying or selectively setting the thickness of the transmission element or the transmission diaphragm.
The transmission element may be configured to be stiffer than the diaphragm or steel diaphragm. Therefore, adjustment inaccuracies during assembly carry over correspondingly less sharply to the transmission element than to the diaphragm. The steel diaphragm or diaphragm deflects outwardly to a greater degree than the transmission element deflects inwardly.
The first measuring element and/or the second measuring element may be configured as a bar or tongue in a chip, the two measuring elements being disposed in a single chip, which consequently forms a measuring chip.
The pressure sensor may have at least two measuring ranges, e.g., the first measuring range covering a range of 0 to 20 bar, e.g., 0 to 10 bar or 0 to 2 bar, while, e.g., the second measuring range covers a range of 0 to 300 bar, e.g., 0 to 250 bar or 0 to 200 bar.
The pressure sensor may have
Cavalloni Claudi
Eickhoff Martin
Gnielka Marco
Krötz Gerhard
Richter Christoph
EADS Deutschland GmbH
Ferguson Marissa
Kenyon & Kenyon
Nolan, Jr. Charles H.
LandOfFree
Pressure sensor, a method for manufacturing a pressure... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pressure sensor, a method for manufacturing a pressure..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pressure sensor, a method for manufacturing a pressure... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3200003